1. Field of the Invention
The present invention relates generally to ophthalmic instruments and, more particularly, to an ophthalmic aspirator-irrigator useful during extracapsular cataract surgery.
2. The Prior Art
Extracapsular cataract surgery involves the break-up and removal of the cortex of the cataract and other tissue from the eye by an aspirator instrument and the continuous substitution of fluids back into the eye to maintain appropriate internal pressure therein lest it collapses. Extracapsular cataract surgery is typically performed with small and delicate manually operated hand-held instruments viewed through a microscope. The precision and delicateness with which ophthalmic surgery is performed requires very durable precision instruments. A great variety of such precision instruments are presently in use. One such instrument employs a pulsating high velocity liquid jet to disintegrate the cortex and removing by suction the fluid entraining the disintegrated tissue. See U.S. Pat. No. 3,930,505. Another instrument uses a pair of jaws for engaging the cortex and removing portions thereof by moving the jaws relative to one another. See U.S. Pat. No. 3,996,935. A further instrument involves one blade surface rotating relative to another. See U.S. Pat. No. 4,167,943. Another instrument includes a rotating stylus, a fluid source for washing away cut tissue and a vacuum tube for removing slurry consisting of the cut tissue and washing fluid. See U.S. Pat. No. 4,320,761. A still further instrument uses a handpiece with an ultrasonic motor for driving a needle, including a cutting tube mounted within a needle, with irrigation and aspiration also provided. See U.S. Pat. No. 4,428,748. Another instrument discloses an automatically operated device, which can be held and operated in one hand by the user and which does not utilize long tubing in operation and wherein the controls are mounted on the handpiece itself. See U.S. Pat. No. 4,508,532. As observed in this Pat. No. 4,508,532, the pumps are connected to the aspiration cannula by long flexible tubing. Such connection can cause fluctuations in the aspiration pressures and time delays in the operation of the instruments.